Plural scale telemetering indicating system



Dec. 5, 1950 L. M. CAMPANI 2,533,09

PLURAL SCALE TELEMETERING INDICATING SYSTEM Filed Feb. 14, 1947 2 SheeS-Sheeb 2 Patented Dec. 5, 1950 PLURAL SCALE TELEMETERING INDICATING SYSTEM Louis M. Campani, Freeport, N. Y., assignor to The Liquidometer Corporation, Long Island City, N. Y., a. corporation of Delaware Application February 14, 1947, Serial No. 728,415

8 Claims. 1

This invention pertains to telemetric instruments and apparatus for indicating the magnitude of a condition, for example, the quantity of liquid in a tank.

In the measurement of fuel in aircraft, a reading of the indicator as the tank approaches empty becomes of increasing importance. From it a pilot must determine his remaining flying time and judge when he must come in for a landing. For such service the lower part of the scale becomes quite critical and it is advantageous to have that portion of the scale as long as possible in order to increase both the accuracy and the readability of the system.

Methods have been used in the past to increase the length of the lower portion of the scale. For example, it is possible to design a transmitter which has higher resistance density at the low end of the element, and a low resistance density at the high end of the element. In such cases it has been possible to register the iirst quarter of the contents of the tank on the iirsthalf of the chart, leaving the other three quarters for the second half of the chart. It is also possible to increase the spacing of the readings at the lower end of the chart mechanically by a suitable arrangement of the linkage system. Such methods, however, have the disadvantage that they improve one part of the scale at the expense of the other.

In the present invention the benet of :a longer scale, or chart, for the lower part of the tank is obtained without sacrificing any other part of the scale. This is obtained by providing two scales of equal length, one to operate over the total capacity of the tank, the other over any desired subdivision of the tank. In this manner a much longer effective scale is obtained than could be attained by the above mentioned methods since aV comparatively small section of the scale may be amplified over the full range of the indicator. This may be achieved either manually or automatically as will appear. As illustrated and described, only two scales are provided, but more than two may be used if desired.

Further and other objects and advantages will be apparent from the speciiication and claims, and from the accompanying drawings which illustrate what is now considered the preferred embodiment of the invention.

In the drawings:

Fig. l shows a system for automatic operation;

Fig. 2 is a modication of Fig. l, for manual operation, and

Fig. 3 is an alternative method for manual operation.

In Fig. 1 the indicator I Iv is of conventional design except that the dial is provided with two scales Ha and IIb. The lower scale IIb is arranged so that it is a fraction of the main scale Ila. For example, if main scale` Ila is 100 gallons, the auxiliary scale IIb may be 25 gallons or any other desired subdivision of 100. The instrument I I shown in the drawings is of the ratiometer type and has a single indicator pointer IIc cooperating with both scales Ha and Hb. The position of the pointer is controlled by the resultant of the flux developed by two deilecting coils I Id and I Ie in a conventional manner. The amplitude of the pointer movement may be controlled by a third coil Hf, current ow through which is constant.

The tank unit, or transmitter, I2 is composed of two resistance elements I2a and I2b. Wipers I2C, I2d and I2e are mechanically rigidly con-l nected together, but are electrically separate. Resistance element I2a may have the same resist-` ance as element I2b, for example 200 ohms. However, resistance element I2b extends throughout the complete range of the travel of its wiper I2d, while in element I2a the same resistance is concentrated over the portion of the travel of wiper ic which it is desired to spread over thejfull movement of the indicator. Over the-remainder of its displacement the wiper I2c may be made to travel on a track I2] of preferably conductive low resistance material. Each resistance element I2@ and I2b and their respectively associated wipers 2c and I 2d may be considered a voltage dividing means. p

Also cooperating with the resistance'elements IZa and I2b is a control switch of standard defsign composed of two strips of conducting matef rial IZg and I 2h. A wiper-I2e is arranged to make contact on either segment depending upon the position of the variable quantity. The position of the three wipers may, in a typical illustration, be controlled by the position of a float F in a tank.

A relay or solenoid I3 is used to obtain automatic action. This relay is composed of a coil 13a, one set of single-pole-single throw contacts Ib and I3c, and one set of single-pole-double throw contacts i3d, I3e and I3f, Athe contacts Ic, i3d and ISf being stationary and contacts isb and I3e being movably carried by the relay armature. When coil I3a is de-energized contacts I3?) and I3c are open, and contacts I3d and ISe are closed while I3c and I 3f are open. Dropping resistor IA is used to prevent a short of the power supply I 5 as will later be described.

In operation, when the tank is full, all the wipers will be at the right hand side of the transmitter. Coil I3a of relay I3 will be de-energized since it is shorted by a wiper I2e being in contact with switch segment I2g. Contacts I3b and I3c will be open, hence no current will now through resistor I4. Contacts I3e and Iid will be closed, so that indicator I I will at this time be controlled by wiper IZd operating on resistance element I2b. The indicator will continue to be controlled from Wiper I2d, and read on the upper scale Ha until the level drops to .such c low point that wiper 12e shown in Fig'. '2.

y 'automatic' transfer switch if contacts segment lh. When 'this occurs, the lower terminal as shown of relay coil lBa is grounded through segment |211. and is energized. When coil |3a is energized, contacts 13b and 13o are closed as shown in Fig. 1, th-us Eproviding a ground connection which is independent :ott-he ground connection in the tank unit through wiper I2e. Simultaneously, contact Ilfefisopened"from I3d and closes with I3f. At l'this time Jcontrol of the indicator Il is transferred to 'wiper 'I`2'c, which is operating on resistanceelement 1211. il-t will be apparent that viewed from the indicator, when wiperV I2c is at the right-most position v'on its resistance element, and is connected to the indicator, it ifs telectrically :at fthe :s'arne position :as whe'niwiper `l12d lis iat its right-most positionuo'n its resistance element, fandfin turn connected Yto .the indicator. -Hen'ce Whenthe wiper--lzciis connected in circuit, it wflfcause lthe indicator to show full scale again-on the lower scale il lili and continue down to zero in thenormal manner. To eliminate any confusion as to which scale is to -be read, 1a light i6 is-provided (withldropping resistor -I if required) 'to Ago on when the traner occurs indiseating that the lower scale should-ber read.

' The Asystem will also operate iin reverse. In filling, the indicator will operate initially on lthe lower scale. When the v-high point of ith'e low scale yisoreache'd, 'say 25 gallons, wiper I'Z will it takes yto open co'r-ita'cts ffl-3h 'and itc. AThe 'automatic action described in Fig. l may be 'made manual by providing a switch i3 Aas 'The transmitter 452 is essentl-ircughfresistor l'll' only during the short intertially the same las that-of Fig. 1 `except that the F3 'is eliminated.. Wipers |"2'c and- -'Z are :connected tof opposite poles of afswitch so that they can 'be selected at will for controlling the indicator. A light 'V6 andk dropping' resistor l1 are 'used vas in Fig. 1

toindi'cate 'which scale is'tolloe used. In a pref Terre-d embodimentlof'the invention, an auxiliary switch `I95is used 'having contacts ma grounded and :contact FSU connected Adirectly to thewarnlight.

ance element 12b 'and wiper -l'2d `controlling 'the indicator the light will' go on, yindicating that'the operator Vmay"switch to the 'lower' scale. As

Uponfapprorachingvempiw with 'the switch in the right 'hand position Yandthe resistyslfiow-n, this light l5, Fig. 2, will be 'operated by *f theswitch i!!Vv as a sort of low limit indicator so that the light will indicate not" only that 'the switch `l8-m'ay 'be rsl-iii'ted to use the lower scale BUYI'IeS-lonng t0 that' numbered No in Fig. l, but-also'to indicate to thepilo't that he'is dangerously'nearthe endofhis fuel supply. Once wthe switch vI8 has beenA shifted 'to-'its left vhand terminal position, Fig. 2, the indicator I?! when read in vconjunction with the lowerrscale will indi'- cate exactly the" amount of liu'el remaining.

While tlie'invention` has lbeen described in foon'- ne'ctlon with arela'y for 'automatic ober-ation and -af toggle' switch for manual operation, it 'is yentirely within'the scope of this invention, 'in cases wheresuiiicient ypower is `available to provide a control switch operated 'by thewper arm or-'o'ther movable element to produce the same' results. Byt-his method' automaticity is al'liieved without misero-f a relay. For this function, switches `oi the snap type are preferable.

'Fig'. lfsliows a variation of the invention wherein onlyone resistance strip isfused. The system is shown Aor manual operation. *Indicator is similar to Il of the previous illustrations with the -elizception that two dropping resistors are used selected by vmeans of a `manual switch. The purzpose 'of two resistors are described below.

The transmitter of Fig. 3 is now composed of a single strip 2|a -wi-th a tap at 2H? depending onthe desired range of the lower scale. One end of'the strip is grounded such as at 2lc. Tap 2lb is brought fout :to .a switch 23 and may be grounded by that switch when desired.

In operation the system will perform in the now familiar manner with the control switch in A., the positionshown in Fig. '3. Whena lowerlevel suchas. gallons is used, 'the operator will throw switch VA23 which `shorts out the portion 'of the transmitter between 2lb and 2l-c. This returns the wiper to near ground potential which lcauses rthe pointer to return to full scale. It will :be realized that since a por-tion of the resistance element is shorted the voltage across the lindicator willi change. This may not 'be detrimental in al1- cases, however, if it is desired to maintain the indicator voltage (or the voltage across the tank unit) constant, the control switch may be made to -cut in another resistor 22 `which -will maintain a balanced condition.- It will'lbe realized that instead of having completely separate resistors, portions of yone may be lcut in or out as is well known inthe art. It will further be realized that in cases when vvthe power supply 'voltage is. low enoughno dropping resistorswill be required.

The invention has 'been described for use with direct current. If alternating current be used, the elements would be inductances or capacita-nces.

yItis "to `be understood that the invention is not limited to the specific embodiment herein illustrated and described but may be used in other walys without departure from its spirit as defined bly the 4io'llowing claims.

What `i'sclainred is: l. Telemetric apparatus for indicating the magnitude of a condition, comprising a single mechanical 'means movable in a predetermined path in `*accordance with and positioned as a :function 'of the .magnitude of the condition to be indicated, wiper means moved'by `said mechanical means, resistor means including resistor ,portions extending respectively along diierent ranges in 'the movement ci said wiper means, said wiper means electrically contacting said resistor portions, an electrical indicating instrument having a lsingle movable vindicating element 'and a plurality of relatively stationary graduated'scales Icoeperati-ng therewith and graduated to correspond respectively with said ranges of said resistor portions, a ysourceof M. F.; land an electric circuit including said resistor means, said .indicating vvinstrument, said source of E. M'. F., a permanent connection from `said indicating instrument to one end' of said resistor mea-ns, said A" wiper means cooperating with said resistor pormovement of said mechanical means and hence of the magnitude of the condition to be indicated.

2. Telemetric apparatus in accordance with claim l, wherein said electrical indicating instrument has two deiiecting coils for controlling the position of said movable indicating element, and wherein said source oi E. M. F. has one terminal connected to one end of one of said coils and also to one end of said resistor means by said permanent connection, the other end of the first-named 1' coil being connected to one end of the other of said coils and the remaining end of said other coil and the other terminal of said source of E. M. F. being grounded, wherein said wiper means includes a plurality of wipers, a conductor connecting each said wiper to said switching means, and a conductor connecting the interconnection between said two coils to said switching means and selectively connected thereby to one of said wipers.

3. Telemetric apparatus in accordance with claim 1, wherein said resistor means consists oi a single electrical resistor having a single wiper in variable engagement therewith and which is carried by said movable mechanical means, and 5.-.

wherein said circuit includes switching means for selectively connecting different points along said resistor to a single electrically predetermined point in said circuit, said resistor portions extending from one end of said single resistor to said diiferent points respectively.

4. Telemetric apparatus for indicating the magnitude of a condition, including an electrical indicating instrument having a plurality of relatively stationary scales representative of different 115 having two deecting coils, one end of one of ranges respectively of the magnitude of the condition to be indicated, and a single movable indicator pointer cooperating with all said scales; atransmitter for controlling the operation of said indicating instrument and having voltage dividing means including respectively cooperating movable wipers, said voltage dividing means being disposed and arranged to correspond respectively to the ranges of said plurality of scales; electrical connections from said indicating instrument to said transmitter, and means responsive to the magnitude of the condition to be indicated for automatically switching said connections from said indicating instrument selectively to each of said voltage dividing means in a predetermined range respectively of the magnitude of said condition.

5. Telemetric apparatus according to claim 4, wherein said electrical indicating instrument includes a supplemental indicator, and comprises uated scales cooperating therewith, a source of E. M. F., and an electric circuit including said resistors, said indicating instrument, said source of E. M. F., a permanent lconnection from said indicating instrument to one end or" each of said resistors, and switching means effective to connect said wipers selectively with said indicating instrument, the other ends of said resistors being connected to an electrically predetermined point in said circuit, said circuit and said switching means being constructed and arranged to cause a predetermined range of movement of said movable indicating element selectively to represent different predetermined ranges of the movement of said mechanical means and hence of the .f two deiiecting coils, a conductor connecting one end of the rst of said coils with one end of the second of said coils and also connecting these ends through said switching means selectively to said wipers, a conductor connecting one end of said source of E. M. F. with the rst oi said coils and with one end of each of said resistors, and ground connections from the other end of each of said resistors, the other terminal of said Source of El. M. F. and the remaining terminal of the second of Said coils of said electrical indicating instrument.

8. Telemetric apparatus in accordance with claim 6, wherein said electrical indicating instrument comprises a ratiometer type instrument to each of two wipers cooperating with said re- 6. Telemetric apparatus for indicating the fi* magnitude of a condition, comprising a single mechanical means movable in a predetermined path in accordance with and positioned as a function of the magnitude of the condition to be indicated, resistor means including at least two fil electrical resistors having the same electric resistance but disposed and arranged to extend respectively different distances along the path of movement of said mechanical means, a

wiper moved by said mechanical means cooperating respectively with and electrically contacting each of said resistors, an electrical indicating instrument having a single movable indicating element and a plurality of gradsistors respectively, and comprising in addition, solenoid operated switch means for mechanically actuating said single-pole double-throw switch, a circuit arranged to be closed during the time said mechanical means is in a predetermined range of its path of movement for energizing the solenoid to operate said switch means to cause said indicating instrument to cooperate with a predetermined one of said resistors and its respectively associated slider, and a holding circuit for holding said solenoid operated switch means in one of its positions initiated by movement of said mechanical means into any part of said predetermined range, and circuit means associated with said holding circuit and including said soleno1d for (ie-energizing said solenoid notwithstanding said holding circuit upon movement of said mechanical means to a part of its range of movement outside said predetermined range.

LOUIS M. CAMPANI.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 1,263,308 Bristol Apr. 16, 1918 1,850,640 Sperry Mar. 22, 1932' 2,154,066 De Giers Apr. l1, 1939 2,280,775 Mirk Apr. 28, 1942 2,400,190 Clark May 14, 1946 2,405,689 De Giers Aug. 13, 1946 2,448,461 Postal Aug. 31, 1948 

